Hybrid electromechanical coolant pump

Abstract

The invention relates to a coolant pump having an impeller which is arranged on a pump impeller shaft and having a drive device for the impeller, which drive device has a mechanical drive and an electric-motor drive. The impeller shaft is divided into a driving section and a driven section, and an openable and closable clutch is arranged between the driving section and the driven section. Operation of the coolant pump by either the mechanical drive or the electric-motor drive can be dependent upon a predetermined speed of threshold of rotation of the impeller, and/or upon a predetermined power usage threshold.

What is claimed is: 
     
         1 . A method for operating a cooling system for an internal combustion engine, the engine having a supply of a coolant liquid and an impeller on an impeller shaft for circulating the coolant liquid in the engine, the method comprising the steps of:
 providing a coolant pump for rotating the impeller, said coolant pump having both a mechanical drive mechanism and an electrical drive mechanism;   rotating the impeller shaft by said electrical drive mechanism when the speed of the impeller is below a predefined speed threshold; and   rotating the impeller shaft by said mechanical drive mechanism when the speed of the impeller is above the predefined speed threshold.   
     
     
         2 . The method as described in  claim 1  wherein said predefined threshold is about 1500 rpm. 
     
     
         3 . The method as described in  claim 1  wherein the impeller is rotated by said electrical drive mechanism when the power used by the impeller is less than a predefined power threshold. 
     
     
         4 . The method as described in  claim 3  wherein said predetermined power threshold is about 1 kW. 
     
     
         5 . The method as described in  claim 1  wherein the impeller is rotated by said mechanical drive mechanism when the power used by the impeller is above a predefined power threshold. 
     
     
         6 . The method as described in  claim 5  wherein said predetermined power threshold is about 1 kw. 
     
     
         7 . The method as described in  claim 1  wherein said electrical drive mechanism comprises an electric motor. 
     
     
         8 . The method as described in  claim 7  wherein said electric motor is a brushless DC motor. 
     
     
         9 . The method as described in  claim 1  wherein said electric drive mechanism and said mechanical drive mechanism are each operably connected to said impeller shaft. 
     
     
         10 . The method as described in  claim 9  further comprising the steps of:
 providing a clutch mechanism between said electrical drive mechanism and said mechanical drive mechanism; and 
 operating said clutch mechanism to decouple said mechanical drive mechanism from said impeller shaft when the speed of the impeller is less than a predefined speed threshold. 
 
     
     
         11 . The method as described in  claim 10  wherein said predefined speed threshold is about 1500 rpm. 
     
     
         12 . The method as described in  claim 9  further comprising:
 providing a clutch mechanism between said electrical drive mechanism and said mechanical drive mechanism; and 
 operating said clutch mechanism to couple said mechanical drive mechanism to said impeller shaft when the speed of the impeller is above a predefined speed threshold. 
 
     
     
         13 . The method as described in  claim 11  wherein said predefined speed threshold is about 1500 rpm. 
     
     
         14 . The method as described in  claim 1  further comprising the step of:
 rotating said impeller shaft by said mechanical drive mechanism at any speed of the engine if there is an electrical failure preventing said electrical drive mechanism from operating. 
 
     
     
         15 . The method as described in  claim 9  further comprising the step of providing an electromechanical clutch mechanism positioned between said electrical drive mechanism and said mechanical drive mechanism. 
     
     
         16 . The method as described in  claim 9  further comprising the step of providing a hydraulically operated clutch mechanism positioned between said electrical drive mechanism and said mechanical drive mechanism. 
     
     
         17 . The method as described in  claim 16  wherein said hydraulically operated clutch mechanism is driven by back pressure from the coolant circuit. 
     
     
         18 . The method as described in  claim 16  wherein said hydraulically operated clutch mechanism is driven by electrical power from the electrical drive mechanism. 
     
     
         19 . The method as described in  claim 16  further comprising the step of providing a valve and recirculating system for operation of said hydraulically operated clutch mechanism. 
     
     
         20 . A cooling system for an internal combustion engine, comprising:
 an internal combustion engine, said engine comprising fluid for cooling said engine;   a temperature sensor for determining the temperature of said coolant fluid;   a cooler member for dissipating heat from said coolant fluid and reducing the temperature of said coolant fluid;   a coolant pump assembly for circulating said coolant fluid through said internal combustion engine and said cooler member whenever base flow and peak flow are needed;   a control system for operating said coolant pump assembly based on data provided by said temperature system;   said coolant pump comprising a mechanically driven pump mechanism and an electrically driven pump mechanism arranged in series;   said coolant pump further comprising a clutch mechanism; and   said mechanically driven pump mechanism being connected by said clutch mechanism in a pulley member which is connected in turn by a belt member to said internal combustion engine and driven at input speed;   wherein said coolant pump is operated by said electrically driven pump mechanism whenever base flow is needed; and   wherein said coolant pump is operated by said mechanically driven pump mechanism only when peak coolant flow is needed.   
     
     
         21 . The cooling system as described in  claim 20  wherein said cooler comprises a radiator mechanism. 
     
     
         22 . The cooling system as described in  claim 20  wherein said electrically driven pump mechanism comprises a brushless DC electric motor. 
     
     
         23 . The cooling system as described in  claim 20  further comprising a plurality of temperature sensors for providing data to said control system. 
     
     
         24 . The cooling system as described in  claim 20  wherein said control system comprises an electronic control unit. 
     
     
         25 . The cooling system as described in  claim 20  wherein said coolant pump is operated by said electrically driven pump mechanism when the volume of coolant flow is below about 150 liters/min. 
     
     
         26 . The cooling system as described in  claim 20  wherein said coolant pump is operated by said mechanically driven pump mechanism when the volume of coolant flow is about 400-450 liters/min. 
     
     
         27 . The cooling system as described in  claim 20  wherein said coolant pump is operated by said electrically driven pump mechanism when the power consumption is below about 1 kW. 
     
     
         28 . The cooling system as described in  claim 20  wherein said coolant pump is operated by said mechanically driven pump mechanism when the power consumption is above about 1 kW. 
     
     
         29 . The cooling system as described in  claim 20  wherein said coolant pump is driven by said electrically driven pump mechanism when the temperature of the coolant pump is below about 90° C. 
     
     
         30 . The cooling system as described in  claim 20  wherein said coolant pump is driven by said mechanically driven pump mechanism when the temperature of the coolant pump is below about 94° C. 
     
     
         31 . The cooling system as described in  claim 20  wherein said coolant pump is driven by either said electrically driven pump mechanism or said mechanically driven pump mechanism when the temperature of the coolant is in the range of about 90° C. to 94° C.